title: Surfactant-free water-processable photoconductive all-carbon composite.
abstract: Heterojunctions between different graphitic nanostructures, including fullerenes, carbon nanotubes and graphene-based sheets, have attracted significant interest for light to electrical energy conversion. Because of their poor solubility, fabrication of such all-carbon nanocomposites typically involves covalently linking the individual constituents or the extensive surface functionalization to improve their solvent processability for mixing. However, such strategies often deteriorate or contaminate the functional carbon surfaces. Here we report that fullerenes, pristine single walled carbon nanotubes, and graphene oxide sheets can be conveniently coassembled in water to yield a stable colloidal dispersion for thin film processing. After thermal reduction of graphene oxide, a solvent-resistant photoconductive hybrid of fullerene-nanotube-graphene was obtained with on-off ratio of nearly 6 orders of magnitude. Photovoltaic devices made with the all-carbon hybrid as the active layer and an additional fullerene block layer showed unprecedented photovoltaic responses among all known all-carbon-based materials with an open circuit voltage of 0.59 V and a power conversion efficiency of 0.21%. The ease of making such surfactant-free, water-processed, carbon thin films could lead to their wide applications in organic optoelectronic devices.
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Vincent C
authors.initials: VC
authors.lastname: Tung
authors.forename: Jen-Hsien
authors.initials: JH
authors.lastname: Huang
authors.forename: Ian
authors.initials: I
authors.lastname: Tevis
authors.forename: Franklin
authors.initials: F
authors.lastname: Kim
authors.forename: Jaemyung
authors.initials: J
authors.lastname: Kim
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Chu
authors.forename: Samuel I
authors.initials: SI
authors.lastname: Stupp
authors.forename: Jiaxing
authors.initials: J
authors.lastname: Huang
mesh_terms: D037741:Fullerenes / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010316:Particle Size; D055668:Photochemical Processes; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D037741:Fullerenes; D037742:Nanotubes, Carbon; D014867:Water; D006108:Graphite